Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Merge ".gitreview: Add defaultbranch" into stable/euphrates
  - .gitreview: Add defaultbranch

    Change-Id: I9c19e81844b1e35907ac79962d8838cc5365601f
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index c116feb..260ad11 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit c116feb5ee3f7535fa737bb81d7a288cc6d434b9
+Subproject commit 260ad1174ad63d9f4c18040ee2dc924a61506778